actually, i'd have a lot more use for a bunch of peasants than a horde of mongols (faveral's medieval market, or medieval tavern).   have you been to the dystopian construction yard?  there's an audience hall that will need hundreds of drab citizens, tens of peacekeepers, and 20 or 30 gliterati.

there are many types of crowds, and how many "when armies clash" images can one person do?